Lightning arrester



L. A. cUsHMAN 2,922,913 LIGHTNING ARRESTER Filed Nov. 19, 1958 Jan. 26,` 1960 INVENTOR LESTER A. CUSHMAN ATTORNEYS LIGHTNING v ARRESTER Lester A. Cushman, Manchester,N.H.

Application November 19, 1958, Seal No. 774,861

6 Claims. (Cl. 313-225) This invention relates to electricity and more particularly to a lightning arrester for connection in a coaxial cable to automatically protect equipment connected to such cable from damage due to heavy surges of static electricity or by reason of lightning striking the cable or an antenna or other equipment connected thereto.

Heretofore, many types of lightning arresters have been proposed and utilized and these have been relatively effective for the purpose intended particularly for protecting radio. apparatus and the like which operates at a relatively low frequency but unfortunately where high frequency equipment is utilized, lightning arresters installed in the coaxial cable or other transmission line connected to the .equipment have introduced excessive losses and have also adversely affected the standing wave ratio.

It is accordingly an object of the invention to provide a lightning arrester which may be conveniently connected in a coaxial cable by utilizing conventional coaxial cable connectors and which will operate to adequately protect apparatus connected thereto from damage due to. heavy surges of static electricity or from lightning striking the cable or other equipment.

A further object of the invention is the provision of a lightning arrester for connection ina coaxial cable which may be conveniently and economically constructed from readily available materials and installed in a coaxial cable without necessitating use of special tools or requiring highly skilled labor.

A still further object of the invention is the provision ofra lightning arrester for connecting in a coaxial cable which will operate to adequately protect equipment connected thereto and at the same time, introduces substantially no added losses and does not adversely aiect the standing wave ratio particularly in applications where the frequency is 150 megacycles or below.

Another object of the invention is the provision of a lightning arrester for connection in a coaxial cable in which a spark gap is provided for draining off to ground heavy surges of static electricity and in which in the event of a direct lightning strike, the parts will fuse together to provide a direct path to ground thereby protecting equipment connected to the cable.

Further objects and advantages of the invention will .be apparent from the following description taken in conjjunction with the accompanying drawing wherein:

Fig. 1 is a longitudinal sectional view showing a lightning arrester constructed in accordance with this inven- Jtion; and

Fig. 2 is a sectional View taken substantially on the filine 2-2 of Fig. 1.

With continued reference to the drawing, there is shown .f a lightning arrester constructed in accordance with this invention and which may Well comprise an elongated tubular body 1i) having a coaxial cable connector 11 at s one end thereof. Connector 11 may be provided with an :iV ing material 14. The coaxial cable to which the lightning arrester of this invention is to be connected is provided with a male connector for insertion in a female connector 13 and with an outer conductor which is engaged by the threaded shell 15 forV clamping the conductor in place on the lightning arrester.

The opposite end of the body 10 is also provided with a coaxial cable connector 16 which may well comprise an outer interiorly threaded rotatably mounted shell 17 provided with an inwardly projecting ange 18 which engages behind a shoulder 19 on a central member 20 which is secured to the body 10 in any suitable manner. The cable connector 16 is also provided with a center male connector 21 spaced from the shell 17 and member 20 by suitable insulating material 22. It is, of course, assumed that the insulating material 14 and 22 will be of such a character as to provide the necessary insulating characteristics at the frequency at which the lightning arrester of this invention is to be utilized.

A sleeve 23 is fixed to the female connector 13 in any suitable manner and a portion 24 of the sleeve 23 projects into the body 10 and terminates in an outwardly extending ilange 25 the purpose of which will presently appear. A central conductor 26 of any suitable material is connected between the sleeve 23 and the male connector 21 and in a normal operation of the device, this conductor 26 provides a suitable path for ow of electrical current through the device from the central conductor of the coaxial cable. The outer conductor of the coaxial cable is, of course, connected to the body 10 of the lightning arrester of this invention and the path of flow of current is through such body and associated parts.

As best shown in Fig. 2, a plurality of radially disposed electrodes 27 are threadedly received in the wall of the body 10 and extend therethrough to provide adjusting heads 28 exteriorly of the body 10 and to provide pointed ends 29 within the body 10 and in spaced concentric relationship to the ange 25 on the sleeve 23. The electrodes 27 may be adjusted to provide a suitable spacing between the inner pointed ends 29 and the ange 25 in order to permit passage of current from the ilange 25 to the electrodes 27 when the voltage reaches a predeter` mined point which is determined by the spacing of the electrodes from the flange 25.

A suitable binding post in the form of a screw orv other suitable means 3i) may be secured to the body 10 and nuts 31 on the screw 30 serve to facilitate attachment of a grounding conductor to thebody 10, and of course the opposite end of the grounding conductor willbe connected to a suitable ground such as a cold water pipe or a pipe or rod driven iiit`` tleearth.

The operation of the lightning arrester of this invention appears clear from the above description of the structure thereof, and it is only considered necessary to state that the lightning arrester is connected in a coaxial cable by utilizing the conventional coaxial cable connectors and the binding post 30 is connected to ground through a suitable conductor. Thereafter in the event of heavy surges of static electricity, such electricity will jump the gap between the flange 25 and the inner ends 29 of electrodes 27 and will be drained oi to ground through the grounding conductor, but in the event of a direct lightning strike on the cable or an antenna or other equipment connected thereto, the ange 25 and inner-- ends 29 of the electrodes 27 will fuse together thereby providing a direct low resistance path to ground through the grounding conductor and thereby drain oit the lightning surge thereby protecting equipment connected to the coaxial cable.

Since the lightning arrester of this invention in reality merely constitutes a specific form of a coaxial cable and is connected in series with a conventional coaxial cable,

no additional losses are introduced therein and there isY no appreciable eiect on the standing wave ratio at any frequencies below 150 megacycles. The device of this invention may be very economically constructed and even though it is necessary to replace the same after a direct lightning strike, nevertheless the cost isso smallas to be unimportant. The device also operates to protect apparatus frornheavy'surges of static Which Wouldotherwise materially damage the same.

lt will Vbe obvious to those skilled in the art that various changesmay be made in the invention Without departing from-the spirit and scope thereof and therefore the inventionis not limited by that which is shown in the drawing and described in the specilication, but only as indicated in the appended claims.

What-is claimed is:

l. For connection in a coaxial cable a lightning arrester comprising an elongated tubular body, a coaxial cable connector on one end of said body, said connector having an outer exteriorly threaded shell and a center female said sleeve and said male connector, a plurality of radially disposed adjustable electrodes extending through the wall of said body and terminating in spaced relation to said tlange and means on said body for facilitating connection of a grounding conductor thereto.

2. For connection in a coaxial cable a lightning arrester comprising an elongated tubular body, a coaxial cable connector on one end of said body, said connector having an outer shell and a center female connector spaced from said shell by insulating material, a coaxial cable connector on the opposite end of said body, said last named connector having an outer shell and a center male connector spaced from said last named shell byinsulating material, a sleeve iixed to said female connector and projecting into said body, a ange on the inner end of said sleeve Within said body, a central conductor extending through said body in coaxial relationship and connecting said sleeve and said male connector, a plurality of radially disposed adjustable electrodes extending through tlwall of said body and terminating in spaced relation to said ilange and means onsaid body for facilitating connection of a grounding conductor thereto.

3. For connection in a coaxial cable a lightning-arrester comprising an elongated tubular body, ka coaxial cable connector on oneend of said body, said connector having an outer shell and a center female connector spaced from said shell by insulating material, a coaxial cable connector on the opposite end of said body, said last named connector'having an outer shell and a center male connector spaced from said last named shell by insulating material, a sleeve iixed to said female connector and projecting into said body, a ange on the inner end of said sleeve within said body, a central conductor extending through said body in coaxial relationship and connecting said sleeve and said maleconnector, at least one radially disposed adjustable electrode extending through the wall of said body and terminating in spaced relation to said ange and means on said body for facilitating connection of a grounding conductor thereto.

4. For connection in a coaxial cable a lightning arrester comprising an elongated tubular body, a coaxial cable connector on one end of said body, said connector having an outer shell and a c enter female connector spaced from said shell by insulating material, a coaxial cable connector on the opposite end of said body, said last named connector having an outer shell and a center male connector spaced from said last named shell by insulating material, a sleeve fixed to said female connector and projecting into said body, a central conductor extending through said body in coaxial relationship and connecting said eleeve and said male connector, at least one radially disposed adjustable electrode extending through the Wall of said body Vand terminating in spaced relation to said sleeve and means on said body for facilitating connection of a grounding conductor thereto.

5. For connection in a coaxial cable a lightning arrester comprising an elongated tubular body, a coaxial cable connector on .each end of said body, each connector having a center and an outer connector, a sleeve fixedy to the center connector at one end of said body and projecting into said body, a central conductor extending through said body in coaxial relationship and connecting the center connections at each end of said body, at least one radially disposed adjustable electrode extending through the wall of said body and terminating in spaced relation to said sleeve and means on said body for facilitating connection of a grounding conductor thereto.

6. For connection in a coaxial cable a lightning arrester comprising an elongated tubular body, a coaxial cable connector on each end of said body, each connector including a center connector and an outer connector, asleeve fixed to the center connector at one end of said body and projecting into said body, a central conductor extending through said body in coaxial relationship and connecting said center connectors, at least one electrode on said body extending inwardly and terminating in spaced relation to said sleeve and means on said body for facilitating connection of a grounding conductor thereto.

No references cited. 

